The only known example of the 1915 $2 Hall of Classics invert on cover has sold as top lot as part of a Hong Kong auction of Fine Stamps and Covers of Hong Kong and China, which was held on January 13.

The stamp is considered one of the Four Treasures of the Republic

Leading among some of the finest rarities in Chinese philately, the cover sold for $619,142.

The error stamp, which has been printed with its central vignette inverted, originates from the foundation of the Chinese Republic in 1912, when a new set of stamps was issued in China. These were originally printed by English printers Waterlow and Sons, though the first world war made it difficult to obtain supplies.

As a result, China was forced to print its own supplies of the stamp in Peking, and a handful of these were found to have been printed incorrectly. The error now sees some of the highest prices among Chinese stamps at auction and is regarded as one of the "Four Treasures of the Republic".

Republic of China stamps are some of the most valuable in the nation's postal history

Also featuring was a fantastic single example of the $2 invert stamp, which displayed its lower margin with a partial imprint. Boasting a large part of its original gum, having been mounted in the margin only, it sold for $154,787.

Another stunning example sold for $160,000 - a 6.6% increase on its $150,000 estimate - as part of a September 2012 auction, suggesting a fair price was achieved in the present sale.

The current world record for any Republic of China stamp is held by another of the "Four Treasures", a $2 Dr Sun Yat Sen inverted pair, which sold for $707,700 in October 2012.  

Paul Fraser Collectibles has perhaps the most sought after stamp in Hong Kong philately, the unique 96c olive-bistre block of four, for sale.